Improvement in locks for prison-doors



2SheetsSheetlv. S. A. DENIO.

' LOCKS FOR PRISON-DOORS. No.173,775', Patented Feb. 22, 1876.

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2 Sheets-Sheet 2.

S., A. DENIO. LOCKS FORPRISON-DOORS.

Patented. Feb. 22,1876.

UNITED-STATES PATENTOFFTCE.

, SYLVANUS A. DENIO, or osToivQMAssAoHUsnTcrs.

IMPROVEMENT INLOCKS FOR PRISON-DOORS.

Specification forming part of Letters Patent No. 173,775, dated February 22, 1876; application filed January 21, 1876.

To all whom it may concern Be it known that I, SYLVANUS. A. Demo, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Looks for Prison-Doors, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which Figure 1 is a. perspective View of a prisondoor lock constructed in accordance with my invention. Fig. 2 is a horizontal section through the same. on the line .00 w of Fig. 2., Fig. 4 is an elevation of the cheek-lock with its front plate removed. Fig. 5 is an elevation of'the checklock, the front plate and tumblers being re moved.

.. against the resistance of its spring, which is liable to become set, so that it will not throw out the check-bolt, and the lock is thus rendered worthless.

To overcome this difficulty is the object of my invention, which consists in the combination, with the camshaft of the main bolt, of a drop bolt or latch, which falls by its own weight into aposition to prevent the rotation of the cam-shaft after the main bolt has been thrown out, the drop bolt being raised to release the cam-shaft by a suitable key, by which construction the spring heretofore used is dispensed with, and the lock rendered at all time reliable.

To enable others skilled-in the art to understand and use my invention, I will proceed to describe the manner in which I have carried it out. v

1n the said drawings, A represents the casing Fig.3 is a vertical section- 'with the shaft, and on this projection rests the outer end of a drop bolt or latch, O, which is pivoted at e within the casing D of the checklock, its outer portion being made heavy to' insure its dropping by its own weight as soon as the cam-shaft has been rotated suificiently to carry the projection d out of contact with the end of the latch, which takes place as soon as the main bolt B has been thrown out. When the parts are in this position, as seen in Fig. 3, the cam-shaft is securely locked, and the bolt B cannot be withdrawn until the latch U of the check-lock is raised by the key f, which acts on its under side, as seen in Fig. 5.

It will thus be seen that, as the drop-latch falls by its own weight, it is always ready to act, and consequently there is no liability of the lock getting out of order, as is the case where an ordinary spring check-lock is employed.

To the inside of the casing D, near its top, is pivoted the upper end of a lever, g, which extends down into a position to be moved by the key f against the resistance of a spring, h. On one side of this lever g is a curved projection, 13, which, when the latch drops, is thrown by the spring h into a space made to receive it between the latch and a projection, is, on the casing, the projection 0' thus serving as a bolt or stop to eli'ectually lock or secure the latch, which cannot be raised until the projection is withdrawn by the key, thus afl'ording additional security. From the front face of the lever 9 projects a stump, l, which passes through the slots of the tumblers m, which must first be raised by the key into their proper relative positions to allow the lever to be moved so as to withdraw the projection z. These'tumblers, however, form no part of my invention, and may be dispensed with, if desired, although I prefer to employ them on account of the security which they afford. a p

are two stop-pins, which intercept the projection 1 and limit the rotation of the cam-shaft inhither directionQ What I claim as my invention, and desire to secure by Letters Patent, is

l. The drop bolt or latch G, in combination with the cam-shaft b and main bolt B, operating substantially in the manner and for the purpose set forth.

2. I also claim, in combination with the SYLVANUS A. DENIO.

In presence of- P. E. TESOHEMAGHER, W. J. CAMBRIDGE. 

